%strict
%token ID INT NUM

%right '='
%left '+'

%%
prog:
    /* empty */
  | prog stmt
;

stmt: 
    expr ';' 
  | decl    
;

expr:
    ID 
  | NUM
  | INT '(' expr ')' /* typecast */ 
  | expr '+' expr
  | expr '=' expr
;

decl:
    INT declarator ';'
  | INT declarator '=' expr ';'
;

declarator:
    ID 
  | '(' declarator ')'
;

%%

=head1  C++ Ambiguities

This grammar models a problematic part of the C++ grammar — the ambiguity between certain
declarations and statements. For example,

     int (x) = y+z;

parses as either an expr or a stmt.


=head1 SEE ALSO

=over 2

=item * L<http://www.gnu.org/software/bison/manual/html_mono/bison.html#GLR-Parsers>

=item * L<http://en.wikipedia.org/wiki/Significantly_Prettier_and_Easier_C%2B%2B_Syntax>

=item * L<http://www.csse.monash.edu.au/~damian/papers/PS/ModestProposal.ps> 

=item * L<http://www.nobugs.org/developer/parsingcpp/>

=item * Edward Willink's "Meta-Compilation for C++" PhD thesis at L<http://www.computing.surrey.ac.uk/Research/CSRG/fog/FogThesis.pdf>

=back

=cut